^and the Earth might have only just relaxed after all those restless human jerks have finally left it alone.
I have yet to read any of the supplement materials and such - I've finished my first playthrough today after all - but from what I've seen in the game itself, there was absolutely nothing said about what Deus was trying to do.
A (very) brief rundown of what the AI's objectives were supposed to be put in it by its creators (there is always room for unfortunate oversights or deliberate sabotage in such stories) was given, but seeing as how the intro video went, I don't think it is safe to assume that they remained unchanged after the contact with Zohar.
[WARNING: dangerous amounts of headcanon below this point]
I like to think it is something far simpler though. It just tickles my sense of dark irony to headcanon that Deus did not take any of that demiurge business in consideration when it did what it did and just tacked on religious imagery and words on its creations because the people that made it were probably more religious than is healthy (sounds like some of the characters in Xenosaga, if you ask me) and just programmed it this way.
Humans being humans found some hidden meaning and far-reaching unfathomable schemes where there wasn't any. The fact that it pretty much created all the humans that roamed the planet and was literally seen as God by those who were tasked with keeping the plan on track while it was deactivated certainly didn't help though.
Why produce humans if one wants them do anything but wage war and fudge up ecosystems? I can only assume that Deus didn't have much choice in the matter and worked with the best thing it had available at that time - the original Fei. (And maybe Elly. The game is really unclear on this part.) The specifications for hordes of angel-themed robot (cyborg?) nanomachine mooks were provided by Deus' creators, sitting in the databanks looking pretty, all ready for production, yes, but the decisive actions by the unnamed captain in the intro likely made it impossible to produce any practical amount with the resources Deus had available at the time.
So it grabbed what it had on hand, adjusted the 'blueprints' to better suit the task, hardcoded a set of directives that would enable its newest batch of minions to complete it without direct supervision and shut down to conserve resources/energy/whatever Deus runs on.
I think it would be logical to assume that Deus is incapable of actually 'creating' anything - all that was shown to be produced by the thing was made from already existing blueprints and adjusted to the current needs - at the point in time it was shown in the game. Maybe it is not beyond its capability to start developing things on its own, but Deus had been online for a very short amount of time before it got deader than dead, so who knows?
(Maybe the usual way humans develop when plopped on a planet and left to their own devices - generating a lot of inorganic junk natural flora and fauna is unable to recycle quickly enough like glass, plastic, etc and choking the life out said flora and fauna in the process - is a slow and steady method of terraforming that turns the planet in a pile of resources all ready for the taking. Such a thing would likely suit Lavos much more than Deus though.)